Abstract: In view of the problems of fast increase in watercut and low recovery rate of oil reservoirs at the end phase of secondary development of No.2 Gangxi Region, experimental research has been conducted on polymer flooding for the whole block of No.2 Gangxi Region. Through adaptability evaluation on this block and research on numerical simulation, the polymer injection well and injection zones were determined, and the polymer injection scheme was formulated for No.2 Gangxi Region. Through follow-up after polymer injection, it was found that polymer flooding has improved the development effectiveness of No.2 Gangxi Region. Based on the development efficiency, the polymer injection scheme was re-optimized, and the relation between viscosity, slug and oil flooding efficiency was again recognized. The numerical polymer flooding model for oil reservoirs was used to predict the development effectiveness of polymer flooding. The No.2 Gangxi Region has provided a favorable example for the development of the whole block of high watercut oil reservoir by polymer flooding.